What is "swallow-tailed duck"

Swallow-tailed \Swal"low-tailed`\, a.

1. Having a tail like that of a swallow; hence, like a swallow's tail in form; having narrow and tapering or pointed skirts; as, a swallow-tailed coat.

2. (Carp.) United by dovetailing; dovetailed.

   Swallow-tailed duck (Zo["o]l.), the old squaw.

   Swallow-tailed gull (Zo["o]l.), an Arctic gull ( Xema furcata), which has a deeply forked tail.

   Swallow-tailed hawk or Swallow-tailed kite (Zo["o]l.), the fork-tailed kite.

   Swallow-tailed moth (Zo["o]l.), a European moth ( Urapteryx sambucaria) having tail-like lobes on the hind wings.